Heat exchanger tube cleaning apparatus and method of removing a blockage from a tube

ABSTRACT

A cleaning apparatus for removing a blockage from a heat exchanger tube of a steam generator, or the like, having a plurality of tubes extending between a pair of tube sheets. Anchor plate fasteners, which are expandable inside tubes adjacent to the blocked tube, are used to mount an anchor plate to one of the tube sheets. The anchor plate has an opening for aligning in registry with the condenser tube having the blockage and provides a solid platform for mounting either a mechanical device or a fluid pressure device for providing a force against the blockage for removal of the blockage. The cleaning apparatus enables a force to be applied which is significantly greater than that which can be applied with known hand-held devices for removing blockages.

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for removing ablockage from a heat exchanger tube, such as a condenser tube of a steamgenerator.

BACKGROUND OF THE INVENTION

Heat exchanger tubes, such as those provided in a condenser for a steamgenerator, often suffer from blockages which render the tube inoperativeand reduces the efficiency of the steam generator. Various methods havebeen used to remove such a blockage, such as forcing a fluid drivenprojectile or scraper through the tube from an opening in a tube sheet,that aligns a plurality of tubes having openings through which fluid canflow. However, it is not always possible to remove a blockage by thisknown method, especially if the blockage is across the entire opening ofthe tube.

SUMMARY OF THE INVENTION

A tube cleaner is provided for removing a blockage from a heat exchangertube, where the blocked tube is part of an array of tubes and where atube sheet has spaced openings in alignment with open ends of the tubearray. The tube cleaner includes an anchor-plate mountable on the tubesheet, and the anchor plate has a plurality of anchor plate openingspassing through the plate, that are in registry with the openings in thetube sheet. At least one anchor plate fastener is provided on the anchorplate that secures the anchor plate to the tube sheet, with the open endof a blocked tube in registry with another anchor plate opening of theanchor plate. The anchor plate also includes means for mounting thereona tube cleaner apparatus with access to the blocked tube and means forproviding a driving force into the blocked tube, to dislodge and removethe blockage from the tube.

The force for removal of the blockage may be provided, for example, by aflexible coil spring that is inserted through the anchor plate and intothe open end of the tube, where the flexible coil spring is driven by ahydraulic drive to incrementally urge the same against the blockage toclear the blockage from the tube, or by a pressurized water gun thatdislodges the blockage and urges the blockage through the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily apparent from the followingdescription of preferred embodiments thereof shown, by way of example,in the accompanying drawings, wherein:

FIG. 1 is a perspective view of a tube sheet and a blocked tube of anarray of tubes, with the other tubes removed for clarity;

FIG. 2 is a perspective view showing an anchor plate of the tube cleanerof the present invention, with a flexible coil spring of the tubecleaner inserted into a blocked tube;

FIG. 3 is a side view similar to that of FIG. 2 showing an expandedanchor plate fastener of the tube cleaner and the flexible coil springmanually inserted into the blocked tube to contact the blockage;

FIG. 3A is an enlarged view of a portion of FIG. 3 for showing detailsof the anchor plate fastener of the tube cleaner;

FIG. 3B is an enlarged view of a portion of FIG. 3 for showing detailsof a tube entry guide and a quick disconnect connector of the presentinvention;

FIG. 4 is a side view similar to FIG. 3 showing use of a driver for theflexible coil spring, the driver being set in a non-locked position andconnected to a hydraulic advancer in a retracted condition;

FIG. 4A is an enlarged view of a portion of FIG. 4 for showing detailsof the tube entry guide having the driver mounted thereon;

FIG. 4B is an enlarged view of a portion of FIG. 4 for showing detailsof the attachment of the driver to the anchor plate, it is across-sectional view through a central axis of the quick disconnectconnector;

FIG. 5 is a view similar to FIG. 4 showing a gripper of the driver in alocked position with the flexible coil spring;

FIG. 6 is a view similar to FIG. 5 showing completion of a hydraulicadvancer stroke, with the hydraulic advancer in an extended condition,and advancement of the flexible coil spring against the blockage in thetube;

FIG. 7 is a view similar to FIG. 6 showing the gripper of the driverunlocked so that the hydraulic advancer can be pulled back and thegripper locked on the flexible coil spring again, for a furtherincremental advancement of the flexible coil spring;

FIG. 8 shows, in views 8A through 8D, the sequence of the driver and theincremental advancement of the flexible coil spring;

FIG. 9 shows a second embodiment of the heat exchanger tube cleanerwherein a pressurized fluid gun is used in conjunction with the anchorplate, as a method for removing a blockage;

FIG. 10 shows the pressurized fluid gun attached to the tube entry guidefor impingement of the pressurized water from the pressurized fluid gunto remove the blockage from a tube;

FIG. 11 is a side view similar to that of FIG. 10 showing impingement ofthe pressurized water from the pressurized fluid gun to remove theblockage from the tube;

FIG. 11A is an enlarged view of a portion of FIG. 11, for showingdetails of the tube entry guide having the pressurized fluid gun mountedthereon, and

FIG. 12 is an enlarged view of an advancing end of the flexible coilspring for showing a plug attached thereto.

DETAILED DESCRIPTION

The device of the present invention is for use on equipment of the typehaving a plurality of tubes arrayed between two tube sheets to whichends of the tubes are welded or mechanically connected. The equipment ismost often used for exchanging heat to or from a medium inside the tubeto a medium outside the tube. For efficient operation of the equipment,deposits formed on the inside of the tubes must be removed periodically.

FIG. 1 shows one of the tube sheets 1 and, for clarity, only one of thetubes 2. Typically, one tube would be associated with each opening 3 inthe tube sheet. A blockage in the tube is indicated at 4. The blockagemight extend completely across the cross-section of the tube or mightonly partially block the tube. As discussed above, another tube sheetwould typically be connected to the other end of the tube and the tubesheets would have a mirror image arrangement of openings. As shown inthe example of FIG. 1, the openings are typically arranged in an orderlypattern, however, such an arrangement is not necessary for use of thepresent device.

The present device is most useful for deposits on the insides of thetubes that are not removable by known brushes or scrapers that areforced through the tubes with use of water pressure, or the like, as alarger force is possible with the present device. Known devicesprimarily consist of operator-held high-pressure guns, having a nozzlewhich is inserted into the end of the tube, for forcing a brush orscrapper through the tube. In the operator-held high-pressure guns thepressure is limited to that which can be opposed to by the operator. Thepresent device enables the use of much higher pressures, as is discussedbelow.

In order to provide the force required to remove the blockage, an anchorplate 5, which is of a size to extend across a plurality of openings 3in the tube sheet, has preferably two anchor plate fasteners 6 that arearranged to be inserted into two of the plurality of tubes 2, one oneach side of the tube to be cleaned, as shown in FIGS. 2 and 3. FIGS. 3and 3A show more clearly the anchor plate fastener 6 inserted in thetube 2. Although two anchor plate fasteners are shown, any number arepossible in practice of the invention.

Each anchor plate fastener 6 is elongated and is of a diameter slightlyless than the inner diameter of the tube to initially slide into thetube. Then, the anchor plate fastener is expanded in order to contactthe inside surface of the tube to an extent that pressure used forclearing the blockage (to be described below) does not move the anchorplate fastener in the tube. The expandable portion of the anchor platefastener is preferably disposed in the tube near a portion of the tubewhich is surrounded by the tube sheet in order that pressure from theexpandable portion is less likely to damage the tube. Any type of knownanchoring means, in which an outer diameter expands, is possible for usein the present invention.

At a central portion of the anchor plate an anchor plate entry opening8, best viewed in FIG. 2 is provided for positioning in registry withthe tube 2, which is to be cleared. In order to obtain the registry, theanchor plate can be provided with openings, for insertion of the anchorplate fasteners, which are properly spaced relative to the entry opening8 for a particular heat exchanger or the like being repaired, or theopenings 7 in the anchor plate for the anchor plate fasteners can beelongated for easily aligning the anchor plate fasteners 6 and aligningthe entry opening 8 with the tubes, as shown in FIG. 9 at 7.

The anchor plate further includes a means for mounting additionalcomponents of the tube cleaner for cleaning the blocked or partiallyblocked tube. The tube cleaner can provide either a fluid device forremoving the blockage or a mechanical device for applying pressure andremoving the blockage. One means for mounting either of the devices,although in differing manners, is the known quick disconnect connectormanufactured for example by Snap-Tite, Union City, Pa., which is bestviewed in FIGS. 3-3A at 9, and in FIGS. 9 at 9 and 17. As shown in moredetail in FIG. 3B, which is a cross-sectional view through a centralaxis of the quick disconnect connector, one mating portion 9 of thequick disconnect connector is connected to a tube entry guide 10 mountedon the anchor plate. FIGS. 3A-3C show the mating portion 9 attached tothe tube entry guide 10, prior to mounting either the mechanical deviceor the fluid device.

FIGS. 4A-4B show the driver 12 of the mechanical device, mounted to theanchor plate 5 by sliding a slotted portion of the driver, indicated at12 a, to be disposed between the anchor plate 5 and a flange 9 a of thequick disconnect connector. As mentioned above the quick disconnectconnector is used in different manners for mounting either the fluiddevice or the mechanical device and FIG. 9 shows the same mating portion9 of the quick disconnect connector, prior to having the fluid pressuredevice coupled with use of mating portion 17. FIG. 10 shows the fluidpressure device mounted by engaging the mating portions 9 and 17 of thequick disconnect connector. The mating portion 17 preferably is not apart of the driver 12 of the mechanical device, however the other matingportion 9 can remain in place on the anchor plate for later use with thefluid pressure device.

FIGS. 4-8 show the use of the mechanical device of the cleaningapparatus for removing the blockage. The mechanical device includes aflexible coil spring 11 that is preferably initially inserted by handinto the blocked tube. The flexible coil spring 11 is of a diameterslightly smaller than the inside diameter of the tube, and it isinserted until it makes contact with the blockage. An outer diameter ofthe flexible coil spring is preferably 80-90% of the inside diameter ofthe tube. The flexible coil spring is preferably made of metal and is ofa length to enable advancement of the blockage to the distal end of thetube and then finally out the distal opening of the tube, if necessary.The flexible coil spring is of the type referred to as a tensionflexible coil spring in which the wire of the spring is helically wound,with each successive winding being in contact with the previous winding.

FIGS. 4-8 show the driver 12 for advancing the flexible coil spring andapplying pressure on the blockage. The driver 12 includes a mechanicalmeans for locking a gripper 13 on the flexible coil spring with use of alever 14. The gripper is in turn attached to a hydraulic advancer 15which advances the flexible coil spring and which can apply a pressureof up to about 5,000 pounds to the blockage.

Although the flexible coil spring has flexibility, which facilitatestransporting and usage, when it is constrained within the tube 2 it hasthe properties of a solid rod to transfer the force from the hydraulicadvancer 15 to the blockage in the tube. Use of a flexible coil springhaving a diameter less than that indicated above, however, may cause theflexible coil spring to buckle inside the tube and possibly rupturingthe tube.

To provide lateral constraint for the portion of the flexible coilspring outside of the tube and to facilitate feeding the flexible coilspring into the tube, a tube entry guide 10 is provided in the anchorplate entry opening 8 as shown in FIGS. 3A-3C. Preferably the tube entryguide extends a short distance into the tube when the anchor plate ismounted to the tube sheet.

FIGS. 4-6 show the driver 12 in various stages of its usage, and FIG. 8shows the sequence of operation of the driver. In FIG. 4, the flexiblecoil spring 11 is positioned through the gripper 13, however the gripperis not yet locked on the flexible coil spring. In FIG. 5, the lever 14is shown rotated in a counter-clockwise direction so as to lock thegripper on the flexible coil spring. In both FIGS. 4 and 5 a piston 16of the hydraulic advancer 15 is at a retracted position. Also, a distalend of the flexible coil spring is in contact with the blockage 4.

FIG. 6 shows the driver 12 as it is positioned following advancement ofthe piston 16 of the advancer to it's extended position. Advancement ofthe piston moves the flexible coil spring deeper into the tube thusapplying pressure to the blockage in order to advance the blockage inthe tube. Depending on the nature and material of the blockage, theblockage may be fractured into smaller pieces when first advanced,leading to easy removal, or additional movement of the blockage towardthe distal end of the tube may be required, if the blockage is notfreed.

FIG. 7 shows the lever 14 rotated clockwise from the position shown inFIG. 6, thus releasing the locking of the gripper on the flexible coilspring. Following the releasing from the flexible coil spring, thepiston 16 of the hydraulic advancer 15 is free to return to theretracted position in order to carry out additional advancements of theflexible coil spring.

FIG. 8 shows the above described sequence for advancing the flexiblecoil spring. The sequence begins at 8A at the top drawing and advancesas indicated by the arrows to finish at 8D. The sequence can be repeatedas many times as necessary until the blockage is removed.

As mentioned above, the blockage may fracture into smaller pieces withone application of the pressure, however it might be necessary toadvance the blockage entirely to the end of the tube in order to removeit. Upon elimination of the blockage, the flexible coil spring can beremoved from the tube manually by releasing it from the gripper andpulling it backward out of the tube. With the coil spring beingflexible, it is easily stored or transported.

In some applications a plug 20, as shown in FIG. 12, can be used at theadvancing end of the flexible coil spring. Preferably, the plug has adiameter slightly larger than the outer diameter of the flexible coilspring, and it can have threads for screwing into the hollow core of theflexible coil spring. A flat advancing face is preferred on the plug.

Another method for removing a blockage is with the use of a liquid underhigh pressure. The anchor plate, described above, along with the tubeentry guide 10, is used for connecting the above-discussed quickdisconnect connector 9, as shown in FIGS. 9-11. Preferably, when thehigh pressure liquid device is used, an 0-ring, or the like is usedbetween the outer surface of the tube entry guide and the inside of thetube, in order to prevent leakage of the high pressure liquid.

The high pressure liquid device is attached to a high pressure source offluid, such as water, having a pressure up to about 2000 pounds/in². Apreferred operating range is from about 800-2000 pounds/in². The highpressure fluid gun 18 includes a pressure gauge 19 for use in monitoringthe pressure of the fluid. With use of the anchor plate 5 of theinvention having the tube entry guide 10 and the quick disconnectconnector, it is convenient to switch between the high pressure fluidgun 18 and the driver 12, in order to remove the blockage from the tubein the most efficient manner. FIGS. 4A-B show, in an enlarged view, theanchor plate 5 having the driver 12 mounted, and FIG. 11A shows, in anenlarged view, the anchor plate 5 having the high pressure fluid gun 18mounted.

1. A heat exchanger tube cleaner for removing a blockage in a tube, theblocked tube being part of an array of tubes wherein a tube sheetprovides access to the tubes through openings in the tube sheet inregistry with the tubes, comprising: (a) an anchor plate for mounting onthe tube sheet, the anchor plate having a plurality of anchor plateopenings therethrough in registry with openings in the tube sheet, (b)at least one anchor plate fastener for securing the anchor plate to thetube sheet such that the blocked tube is in registry with another anchorplate opening in the anchor plate, (c) means on the anchor plate tomount a tube cleaning apparatus with access to the blocked tube throughan anchor plate opening, and (d) means for providing a driving forceinto the blocked tube, to clean the blockage from the tube, engageablewith the anchor plate.
 2. A tube cleaner as defined in claim 1, whereinthe driving force is provided by a flexible coil spring insertable intothe blocked tube and wherein the flexible coil spring is operativelyconnected to a hydraulic drive to urge the flexible coil springincrementally against the blockage to clear the blockage from the tube.3. A tube cleaner as defined in claim 1, wherein the driving force isprovided by a pressurized water gun for supplying pressurized water tourge the blockage through the tube.
 4. A tube cleaner as defined inclaim 1 wherein the anchor plate fastener is expandable at a position inthe anchor plate opening of the anchor plate.
 5. A tube cleaner asdefined in claim 1 wherein the anchor plate has a tube entry guidedisposed thereon and a quick disconnect connector secured to the tubeentry guide.
 6. A tube cleaner as defined in claim 1 wherein a pluralityof anchor plate fasteners are provided, each in registry with arespective tube.
 7. A tube cleaner as defined in claim 2 wherein theflexible coil spring has an outer diameter between 80-90% of the insidediameter of the blocked tube.
 8. A tube cleaner is defined in claim 2wherein the flexible coil spring has a plug on the distal end thereof.9. A tube cleaner as defined in claim 3 wherein the pressurized watergun supplies pressurized water at a pressure up to about 800 pounds/in²to remove a blockage from a tube.
 10. A tube cleaner for removing ablockage in a condenser tube, the blocked tube being part of an array oftubes and wherein a tube sheet provides access to the tubes throughopenings in the tube sheet in registry with the tubes, comprising: (a)an anchor plate for mounting on the tube sheet, the anchor plate havinga plurality of anchor plate openings therethrough in registry withopenings in the tube sheet, (b) at least one anchor plate fastenerexpandable at a position in the anchor plate opening, for securing theanchor plate to the tube sheet such that the blocked tube is in registrywith another anchor plate opening in the anchor plate, (c) a tube entryguide disposed on the anchor plate and extending toward the blockedtube, (d) a quick disconnect connector, secured to the tube entry guideon the anchor plate, arranged to mount a tube cleaning apparatus withaccess to the blocked tube, and (e) means for providing a driving forceinto the blocked tube to clean the blockage from the tube, engageablewith quick disconnect connector on the anchor plate, comprising aflexible coil spring insertable into the blocked tube, the flexible coilspring operatively connected to a drive means to urge the flexible coilspring incrementally against the blockage to clean the blockage from thetube.
 11. A tube cleaner as defined in claim 2 wherein the flexible coilspring has an outer diameter between 80-90% of the inside diameter ofthe blocked tube.
 12. A tube cleaner for removing a blockage in acondenser tube, the blocked tube being part of an array of tubes whereina tube sheet provides access to the tubes through openings in the tubesheet in registry with the tubes, comprising: (a) an anchor plate formounting on the tube sheet, the anchor plate having a plurality ofanchor plate openings therethrough in registry with openings in the tubesheet, (b) at least one anchor plate fastener expandable at a positionin the anchor plate opening, for securing the anchor plate to the tubesheet such that the blocked tube is in registry with another anchorplate opening in the anchor plate, (c) a tube entry guide disposed onthe anchor plate and extending toward the blocked tube, (d) a quickdisconnect connector, secured to the tube entry guide on the anchorplate, arranged to mount a tube cleaning apparatus with access to theblocked tube, and (e) means for providing a driving force into theblocked tube to clean the blockage from the tube, engageable with thequick disconnect connector on the anchor plate, comprising a pressurizedwater gun for supplying pressurized water to urge the blockage throughthe tube.
 13. A tube cleaner as defined in claim 12 wherein thepressurized water gun supplies pressurized water at a pressure up toabout 2000 pounds/in² to remove a blockage from a tube.
 14. A tubecleaner as defined in claim 12 wherein the pressurized water gunsupplies pressurized water at a pressure in a range of about 800-2000pounds/in² to remove a blockage from a tube.
 15. A method for removing ablockage in a heat exchanger tube being part of an array of tubes in acondenser and wherein a tube sheet provides access to the tubes throughopenings in the tube sheet in registry with the tubes, comprising:mounting an anchor plate on the tube sheet, the anchor plate having aplurality of anchor plate openings therethrough in registry withopenings in the tube sheet; securing at least one anchor plate fastenerto the tube sheet at an opening in the tube sheet such that the blockedtube is in registry with another anchor plate opening in the anchorplate; mounting a tube cleaning apparatus on the anchor plate withaccess to the blocked tube through an anchor plate opening; providing adriving force, through a driving force means engaged with the anchorplate, into the blocked tube to clear the blockage from the tube.
 16. Amethod of removing a blockage in a tube as defined in claim 15, whereinthe driving force is provided by a flexible coil spring inserted intothe blocked tube and wherein the flexible coil spring is operativelyconnected to a hydraulic drive, urging the flexible coil springincrementally against the blockage to clear the blockage from the tube.17. A method of removing a blockage in a tube as defined in claim 15,wherein the driving force is provided by a pressurized water gun andpressurized water is supplied to urge the blockage through the tube.